After taking delivery and listening to the “upgraded” HK stereo I was very let down. The rear subwoofer rattled and buzzed whenever it got loud enough to actually be heard. To me it almost sounded like the speaker was blown. When I finally got to compare my stereo to Alan’s HK I knew something was not right.
Turns out a rubber, snorkel-tube that is designed to port the sound to a lower position had come loose and was vibrating. The vibrating rubber tube sounded just like what a blown speaker sounds like.
The good news is it was really easy to fix. The speaker grill just pops off, start with the lower corners then the upper corners. With the grill removed you can see this silly little rubber tube thing. The tube just sticks into the open hole in the subwoofer, a couple raised rings try and hold it in there. To me it seemed like it would only be a matter of time before it worked its way loose again. I was considering putting a couple drops of glue on it to help hold the tube in place.
On a whim I tried listening to the stereo with out the tube in at all. Honestly I could not tell a difference with and without the tube so I decided just to leave it off. It’s a piece of cake to reinstall it later if someone convinces me to do so, but for now the rubber tube is tossed onto the pile of other BMW parts in the corner of my garage.
UPDATE 5/10: The subwoofer sounded good at low volume with the tube removed, but with the top down and the stereo at high volume the subwoofer started to sound muddy. After a little experimentation (this time with the volume turned up high) I found that the rubber tube does make the subwoofer sound tighter at high volume. So the rubber tube came back off the pile of parts in the corner of my garage and is now back with the sub woofer. I was tempted to put a couple drops of super glue on it so it would stay, but decided to give it a try without glue first. If the tube works its way loose then I’ll glue it back in.